NASHVILLE, Tenn. - In his songs, Johnny Cash never shied away from life's dark side. It's all there: temptation, murder, incarceration and just plain loneliness.
Now the singer of Folsom Prison Blues and many other hits faces another demon: Parkinson's disease.
The condition threatens his ability to sing and play music, which is all he ever wanted to do.
It's the latest of a long list of health challenges that have plagued the 65-year-old singer, including addictions to amphetamines and painkillers and open-heart surgery in 1988.
Parkinson's attacks the nervous system and erodes motor skills. It is caused by the loss of brain cells that secrete dopamine, a chemical necessary to keep muscle movements smooth and controlled. It is a progressive and incurable disease, though medication can control symptoms such as shaking and drooling.
Mr. Cash's grandfather, William Henry Cash, died of Parkinson's in 1912.
"He knew about it from a physical he had earlier in the fall," said Mr. Cash's manager, Lou Robin. "He had no symptoms at the time, so he didn't attempt to address it. In his mind, he wasn't going to have it, so that was that."
At his last concert, Oct. 25 in Flint, Mich., Cash, almost fell down while bending to retrieve his guitar pick. Two days earlier, he performed in Knoxville, Tenn. A reviewer for The Knoxville News-Sentinel wrote that Mr. Cash's timing seemed off and he didn't appear for an encore.
On Oct. 27, he canceled an appearance in New York to promote Cash: The Autobiography and announced through a news release that he has Parkinson's.
Since then, he has been in seclusion with his family while getting medical advice and considering his future.
"Johnny feels confident that once the Parkinson's is medically stabilized, he can resume his normal work schedule," Mr. Robin said.
Mr. Cash normally performs about 80 concerts a year. He also works in the recording studio and films television commercials.
With treatment, he probably could continue performing, said Thomas Davis, director of the movement disorders clinic at Vanderbilt University Medical Center in Nashville.
"The disease is extremely variable from person to person," said Dr. Davis, who is not treating Mr. Cash. "Certainly, earlier in the disease many performers could continue doing what they normally would do.
"Also, early on it can be fairly local. For example, the right hand could be affected enough to hurt guitar-playing, but someone could still sing."
If retirement ever sounded good to Mr. Cash, he probably would have done it by now. He doesn't need to work. He has sold more than 50 million records, and he and wife, June Carter Cash, own homes outside Nashville, in Jamaica, the British West Indies, and in Port Richey, Fla.
Through four decades of troubles, triumphs and varying degrees of commercial success, Mr. Cash has consistently toured and recorded music. In an interview last year with the Associated Press, he said he had a "burning desire" to continue performing.
In the early days of his career, Mr. Cash scored rock 'n' roll hits like Ballad of a Teenage Queen and was known as an amphetamine-addicted hell-raiser who tore up hotel rooms.
In the 1960s and '70s, he became a country music superstar, weaving folk music, country and gospel into a unique stew. The Johnny Cash Show aired on ABC from 1969 to 1971, one of the first network variety shows with a country music performer as host.
He is the only living member of the Country Music Hall of Fame and the Rock and Roll Hall of Fame.
His country music popularity faded in the 1980s, but in recent years a younger generation discovered him and gave his career new life. His audience these days incorporates senior citizens and people in their 20s.
Since 1994, he has released two CDs on American Recordings, owned by rap-heavy metal producer Rick Rubin. And he has become a hero to younger country music performers who have found themselves, like Mr. Cash, unwelcome in the mainstream of country music.
"Johnny Cash is the John Wayne of country music," said Robbie Fulks, a singer-songwriter from Chicago. "He's unapologetic, gigantic and alone. His singing is too unpretty for country and too dignified for rock. His music at his most powerful makes you wonder if there is a moral quality to human suffering."
Mr. Cash has suffered many medical problems through the years. A pinched nerve in his jaw causes him constant pain, and he was treated for addiction to morphine in 1984 at the Betty Ford Center for Chemical Dependence.
In 1988, he underwent successful double-bypass heart surgery. The next year he entered a drug-and-alcohol treatment center to guard against a relapse after he stopped taking pain medication.
Although Mr. Cash and his family are uneasy about his current condition, they are hopeful the Parkinson's can be stabilized using medication, Mr. Robin said. So far, his only symptom has been equilibrium problems. Experimental surgical procedures will be considered, he said.
"He's faced a lot of challenges in his life," Mr. Robin said. "He thrives on challenges and will deal with this accordingly."
If Mr. Cash can still perform, chances are he will.
In Cash: The Autobiography, he writes that he'd like to "just keel over and die on the stage, under the lights, with my band and my family around me and Fluke (drummer W.S. Holland) still laying down the beat.
"That's every performer's dream, you know."